This invention pertains generally to descent devices, and more particularly to a novel descent device with manually operable brake means to control the descent of the device (and a load) along a suspended line.
It is old in the arts of handling and moving of work with the aid of ropes and lines, to utilize various forms of friction devices to slow and/or to control the relative movement of related lines and work. One group of friction devices consists of those with cylindrical shafts about which lines are wrapped or wound so that a desired frictional drag is produced between the shaft and the line as the line is caused to slide about the shaft under work loads. In one sub-group of such devices, the devices are fixed in position and the lines are moved relative thereto, while in another sub-group, the lines are anchored and the devices move along the line. It is the second sub-group of friction devices with which the present invention is concerned.
The art of descent devices was extremely active and became highly developed throughout the years between about 1875 and about 1925. During those years, such devices were especially designed for use by persons endeavoring to escape from buildings during a fire, and consisted of ropes or lines anchored within the upper stories of the buildings and caused to freely depend at the exterior of the buildings, and descent devices of the type referred to above, engaged with the lines and which the persons exiting the buildings gripped or fastened themselves to and which operated to slow their descent down and along the line.
The above-noted type of descent devices has continued to be used throughout the years and U.S. Pat. Nos. 147,828, 289,050, 292,981 and 386,237 disclose devices of the type with which the present invention is concerned, and show the state of the art prior to the 1900's.
A major deficiency found to exist in the aforesaid descent devices resides in the fact that the devices must be set to normally afford insufficient friction to prevent rapid movement down their related lines and that controlled movement down the lines is achieved by the application of additional friction produced by the users of the devices, as by manually engaging portions of the lines about cleats on the devices and manually drawing the line about the cleats to increase or decrease the frictional drag as required. This not only requires that at least one hand of the user be used to control the operation of the device, but it further requires the exercise of special skills which require special talent and practice to perfect.
A more serious deficiency of the prior art descent devices resides in the fact that if the line should become displaced from the cleat or if the user of the device should lose his grip on the line, uncontrolled free and hazardous descent down the line is likely to result.
In efforts to overcome the above deficiencies, the prior art has taught the use of descent devices with various kinds of manually controlled braking means to enable the users of the devices to control their rate of descent down related lines. Two of these braking means are disclosed in U.S. Pat. No. 536,866 issued Apr. 2, 1895, and U.S. Pat. No. 1,187,754 issued June 20, 1916. Although U.S. Pat. No. 536,866 contains the statement that the brake acts automatically, it is obvious that the only "automatic" force applied to the rope A is the weight of the handle F, which appears to be insignificant, and which actually requires the handle to be manually pulled downwardly by the user to effect a braking action. U.S. Pat. No. 1,187,754 also requires the brake means to be manually applied. Thus, the shaft 10 about which the line is wrapped is of tapered construction; a corresponding tapered sleeve 17 is engaged about the shaft and the line; and cam means actuated by the handle 37 is utilized to shift the sleeve relative to the shaft and into and out of pressure frictional engagement with the line about the shaft.
With the aforegoing limitations and deficiencies of known devices in mind, it is an object of the present invention to provide a novel descent device with manually operable brake means whereby the device is held stationary on the rope and must be manually actuated by the user to provide for a controlled rate of descent.
A further object of the present invention is to provide a descent device of the general character referred to above, in which the control means presents no major projections with which a related line is likely to become entangled or which is likely to cause injury or damage to a person or to objects with which the device may come into contact.
Yet another object of the present invention is to provide an improved descent device wherein the control means is of the "dead-man" type, such that the manual actuation of the control means is necessary to effect controlled descent of the device and its load down a related line, and which is such that loss of manual control of the control means results in stopping movement of the device or results in a predetermined set slow movement down the line.
It is yet another object of the present invention to provide an improved descent device which, in an alternative form, includes manually releasably latch means to hold the control means in brake-released position, and which further includes means to adjust the control means whereby the device can be made to move down its related line at a controlled rate of speed.
Furthermore, it is an object of the present invention to provide an improved descent control device which is easy and economical to manufacture, easy and convenient to use, and which is highly effective and dependable in operation.
The foregoing and other objects and features of the invention will be fully understood from th following detailed description of a typical preferred form and embodiment of the invention, throughout which description reference is made to the accompanying drawings.